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  Encapsulated back-up system for use with seal systemUSPTO Application #: 20070290454Title: Encapsulated back-up system for use with seal system Abstract: Disclosed is an anti-extrusion assembly used in conjunction with an expandable packing device. The assembly comprises two slotted metallic rings encapsulated in a non-metallic material. The slotted metallic rings prevent extrusion of the sealing mechanism of the expandable packing device as the device is set in a wellbore casing. The encapsulating non-metallic material protects the metallic rings from damage as the packing device is run into the wellbore. In an alternative embodiment, the anti-extrusion assembly comprises a crimped metallic ring flanked by non-metallic rings. As with the slotted metallic rings, the single crimped metallic ring prevents extrusion of the sealing mechanism of the expandable packing device as it is set in the wellbore casing. (end of abstract)
Agent: Howrey LLP - Falls Church, VA, US Inventors: Hubert F. Garrison, Douglas J. Lehr, Gabriel Slup USPTO Applicaton #: 20070290454 - Class: 277611000 (USPTO) Related Patent Categories: Seal For A Joint Or Juncture, Seal Between Fixed Parts Or Static Contact Against Relatively Movable Parts, Contact Seal For A Pipe, Conduit, Or Cable, Inserted Between End-to-end Pipe, Conduit, Or Cable Joint, Extrusion Preventing (i.e., Antiextrusion) Or Compression Limiting Feature The Patent Description & Claims data below is from USPTO Patent Application 20070290454. Brief Patent Description - Full Patent Description - Patent Application Claims
CROSS REFERENCE TO RELATED APPLICATIONS [0001] The present application is a divisional application of co-pending U.S. patent application Ser. No. 11/109/574, filed Apr. 19, 2005, which is hereby incorporated by reference in its entirety. BACKGROUND OF THE INVENTION [0002] Expandable packers and bridge plugs are commonly used in the oil and gas industry to seal or close off an annular area in a wellbore casing. Theses packers or bridge plugs typically include a centrally located sealing member that is cylindrically shaped and constructed of rubber or some other elastomeric material. The outer diameter of the sealing member is typically smaller that the inner diameter of the corresponding casing such that the packer or bridge plug can be easily inserted and positioned at the desired location within the casing. [0003] Once correctly positioned, the activation of the packer or bridge plug typically results in a longitudinal compression of the sealing member such that the sealing member is forced outwardly into contact with the casing, effectively sealing the annular area. The sealing member is held in this compressed state by the simultaneous setting of a series of slips. The slips for permanent packers or bridge plugs are typically located above and below the sealing member and, when activated, are cammed outwardly against the casing to anchor the packer or bridge plug in place. Other packers or bridge plugs, particularly the retrievable variety, may have only a single set of slips. [0004] Anti-extrusion or "back-up" assemblies, typically in the form of solid or slotted rings, are positioned adjacent to the sealing assembly, between the sealing assembly and the slips. These back-up assemblies are designed to expand radially and prevent extrusion of the sealing member during activation of the packer or bridge plug. However, the back-up assemblies, particularly the slotted variety, are susceptible to damage when the packer or bridge plug is being run downhole. [0005] Damage to the back-up assemblies can occur due to wellbore fluid rushing past the packer or bridge plug, or due to contact with the casing (especially at transition points such as the transition between the casing and a liner). Contact with the casing often occurs when running the packer or bridge plug through a transition point, such as the entrance to a liner. Damage to the back-up assembly can cause the packer or bridge plug to set prematurely (i.e., at a depth that is less than intended) or leak prematurely. When this happens, the packer or bridge plug must be either retrieved (if it is a retrievable type), or destructively removed from the casing (if it is a permanent type). Both of these alternatives are costly and time consuming. [0006] Accordingly, a need has arisen for a back-up assembly design that protects against damage and eliminates the likelihood of the corresponding packer or bridge plug setting prematurely or leaking after setting. The following invention addresses those needs. SUMMARY OF THE INVENTION [0007] This invention relates to an anti-extrusion assembly used in conjunction with expandable packing devices. More particularly, this invention relates to a back-up assembly used to prevent the extrusion of a sealing member on downhole packers and bridge plugs. [0008] In a first embodiment of the present invention, the back-up assembly comprises an outer metallic ring exhibiting a generally conical shape and including a flat shelf at the narrow end of the outer metallic ring. The shelf includes a longitudinal bore, which exhibits a hexagonal or other suitable polygonal shape. The outer metallic ring includes a series of longitudinal slots, which extend along the entire length of the conical portion of the outer metallic ring, and partially into the shelf. The slots effectively form a series of "petals" in the areas located between the slots. [0009] The back-up assembly further comprises an inner metallic ring exhibiting a generally conical shape and including a flat shelf at the narrow end of the inner metallic ring. The shelf of the inner metallic ring includes a longitudinal bore, which, like the longitudinal bore of the outer metallic ring, exhibits a hexagonal or similar polygonal shape. The inner metallic ring includes a series of longitudinal slots, which extend along the entire length of the conical portion of the inner metallic ring, and partially into the shelf. As with the outer metallic ring, the slots effectively form a series of petals in the areas located between the slots. [0010] The inner metallic ring is placed within the outer metallic ring such that the outer diameter of the inner metallic ring abuts the inner diameter of the outer metallic ring. The inner metallic ring is arranged within the outer metallic ring such that the respective slots and corresponding petals do not overlap. This results in the slots of the inner metallic ring being "covered" by the petals of the outer metallic ring, and vice versa. While the respective slots and petals are not aligned, the opposite is true for the longitudinal bores of the inner metallic ring and the outer metallic ring. [0011] Once the metallic rings are properly arranged, they are encapsulated in an non-metallic material. The encapsulating material does not distort the overall geometry of the metallic rings, including the shape of the longitudinal bores. Rather, the encapsulating material serves to protect the back-up assembly from damage and premature setting due to inadvertent contact with the casing and/or other problems associated with running a packer or bridge plug into a wellbore. [0012] Once encapsulated, one or more back-up assemblies of the present invention are placed onto the mandrel of a packer or bridge plug. The encapsulated back-up assemblies are typically located on either side of a sealing member. The packer or bridge plug is then lowered into a wellbore. Once correctly positioned, the packer or bridge plug is activated, which typically results in the sealing member being forced outwardly into contact with the wellbore casing. Simultaneously, the encapsulated back-up assemblies flare out and expand radially and prevent extrusion of the sealing member. The offsetting alignment of the slots and petals of the outer metallic ring and inner metallic ring leaves no uncovered "gaps." Accordingly, as the sealing member expands, it is prohibited from extruding past the back-up assemblies, and is instead forced into sealing contact with the wellbore casing. [0013] In a second embodiment of the present invention, the back-up assembly comprises a flat metallic disc. The metallic disc includes a longitudinal bore, which exhibits a hexagonal or other suitable polygonal shape. The metallic disc includes a series of slots, which extend radially from the outer diameter of the metallic disc towards the longitudinal bore. The slots effectively form a series of petals in the areas located between the slots. The flat metallic disc is then "crimped" and formed into a metallic ring. The metallic ring exhibits a generally conical shape, but includes a flat shelf extending radially inward at the narrow end of the metallic ring. In this crimped state, the petals overlap each other, thereby effectively eliminating the slots. [0014] The back-up assembly further comprises a non-metallic inner ring. The non-metallic inner ring exhibits a generally conical shape and includes a longitudinal bore, which also exhibits a hexagonal or similar polygonal shape. The inner non-metallic ring is placed within the metallic ring such that the outer diameter of the inner non-metallic inner ring abuts the inner diameter of the metallic ring. As the longitudinal bores exhibit the same geometry, they are aligned such that their respective shapes effectively mirror each other. The back-up assembly additionally comprises a non-metallic outer ring. The non-metallic outer ring is placed around the outer diameter of the metallic ring. While not entirely encapsulating the metallic ring as in the first embodiment, the non-metallic outer ring of this embodiment extends the entire longitudinal length of the metallic ring, including the shelf portion, and will flow through any gaps between the petals in the metallic ring. The three rings comprise the complete back-up assembly. [0015] Once complete, one or more back-up assemblies of the present invention are placed onto the mandrel of a packer or bridge plug. The back-up assemblies are typically located on either side of a sealing member. The packer or bridge plug is then lowered into a wellbore. Once correctly positioned, the packer or bridge plug is activated, which typically results in the sealing member being forced outwardly into contact with the wellbore casing. Simultaneously, the back-up assemblies flare out and expand radially and prevent extrusion of the sealing member. The overlapping of the "crimped" petals leaves little or no uncovered "gaps" as the metallic rings are flared out. Accordingly, as the sealing member expands, it is prohibited from extruding past the back-up assemblies, and is instead forced into sealing contact with the wellbore casing. [0016] In a third embodiment of the present invention, the composition of the back-up assembly is identical to that of the second embodiment, except that an additional anti-extrusion ring has been added. The anti-extrusion ring is added to improve the anti-extrusion capability of the back-up assembly at higher wellbore temperatures. The anti-extrusion ring may either be embedded into the non-metallic inner ring at a point adjacent to the sealing member, or at a point adjacent to the metallic ring. Alternatively, the anti-extrusion ring may be embedded into the non-metallic outer ring. [0017] Additional objects and advantages of the invention will become apparent as the following detailed description of the preferred embodiment is read in conjunction with the drawings. BRIEF DESCRIPTION OF THE DRAWINGS [0018] FIGS. 1a, 1b, and 1c illustrate multiple views of the outer metallic ring component of the back-up assembly of the present invention. [0019] FIGS. 2a, 2b, and 2c illustrate multiple views of the inner metallic ring component of the back-up assembly of the present invention. [0020] FIGS. 3a and 3b illustrate multiple views of the encapsulated back-up assembly of the present invention. Continue reading... Full patent description for Encapsulated back-up system for use with seal system Brief Patent Description - Full Patent Description - Patent Application Claims Click on the above for other options relating to this Encapsulated back-up system for use with seal system patent application. ###  How KEYWORD MONITOR works... a FREE service from FreshPatents1. Sign up (takes 30 seconds). 2. Fill in the keywords to be monitored. 3. Each week you receive an email with patent applications related to your keywords. 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